A field emission device emits electrons in response to an applied electrostatic field. Such devices are useful in a wide variety of applications including displays, electron guns and electron beam lithography. A particularly promising application is the use of field emission devices in addressable arrays to make flat panel displays. See, for instance, the December 1991 issue of Semiconductor International., p. 11. C. A. Spindt et al., IEEE Transactions on Electron Devices, Vol. 38(10), pp. 2355-2363 (1991), and J. A. Castellano, Handbook of Display Technology, Academic Press, New York, pp. 254-257, (1992), all of which are incorporated herein by reference.
Conventional electron emission flat panel displays typically comprise a flat vacuum cell having a matrix array of microscopic field emitter cathode tips formed on one plate of the cell ("the back-plate") and a phosphor-coated anode on a transparent front plate. Between cathode and anode is a conductive element called a "grid" or "gate". The cathodes and gates are typically perpendicular strips whose intersections define pixels for the display. A given pixel is activated by applying voltage between the cathode conductor strip and the gate conductor strip whose intersection defines the pixel. A more positive voltage is applied to the anode in order to impart a relatively high energy (about 1000 eV) to the emitted electrons. See, for example, U.S. Pat. Nos. 4,940,916; 5,129,850; 5,138,237; and 5,283,500.
A difficulty with these conventional flat panel displays is that they are difficult and expensive to make. If conventional approaches the gate conductors typically have important micron or submicron features which require expensive, state-of-the-art lithography. Accordingly, there is a need for an improved electron emission apparatus which can be economically manufactured for use in flat panel displays.